Surgical landmarks of the spinal accessory nerve in modified radical neck dissection.

We designed a study to identify useful landmarks for the preservation of the spinal accessory nerve during modified radical neck dissection (MRND). Eighteen consecutive patients undergoing 23 MRNDs were enrolled in the study. The distance of the accessory nerve from the greater auricular nerve, where it crosses the posterior edge of the sternocleidomastoid muscle (greater auricular point), was noted. The vertical distance between the point of entrance of the accessory nerve into the trapezius muscle and the clavicle was also measured. The mean distance between the greater auricular point and the accessory nerve was 10.7 mm, SD +/- 6.3. In all cases the accessory nerve was above the greater auricular point. The mean distance between the point of entrance of the nerve into the trapezius and the clavicle was 51.3 mm, SD +/- 17. The greater auricular point is a reliable landmark for the identification of the accessory nerve during modified radical neck dissection. Distance above the clavicle was less helpful.